翻译文献-jsp.12 api核心

大连交通大学2016届本科生毕业设计（论文）外文翻译外文原文JSP12COREAPITHISCHAPTERDESCRIBESTHEJAVAXSERVLETJSPPACKAGETHECHAPTERINCLUDESCONTENTTHATISGENERATEDAUTOMATICALLYFROMJAVADOCEMBEDDEDINTOTHEACTUALJAVACLASSESANDINTERFACESTHISALLOWSTHECREATIONOFASINGLE,AUTHORITATIVE,SPECIFICATIONDOCUMENTTHEJAVAXSERVLETJSPPACKAGECONTAINSANUMBEROFCLASSESANDINTERFACESTHATDESCRIBEANDDEFINETHECONTRACTSBETWEENAJSPPAGEIMPLEMENTATIONCLASSANDTHERUNTIMEENVIRONMENTPROVIDEDFORANINSTANCEOFSUCHACLASSBYACONFORMINGJSPCONTAINERJSP121JSPPAGEIMPLEMENTATIONOBJECTCONTRACTTHISSECTIONDESCRIBESTHEBASICCONTRACTBETWEENAJSPPAGEIMPLEMENTATIONOBJECTANDITSCONTAINERTHEMAINCONTRACTISDEFINEDBYTHECLASSESJSPPAGEANDHTTPJSPPAGETHEJSPFACTORYCLASSDESCRIBESTHEMECHANISMTOPORTABLYINSTANTIATEALLNEEDEDRUNTIMEOBJECTS,ANDJSPENGINEINFOPROVIDESBASICINFORMATIONONTHECURRENTJSPCONTAINERNONEOFTHECLASSESDESCRIBEDHEREAREINTENDEDTOBEUSEDBYJSPPAGEAUTHORSEXAMPLEOFHOWTHESECLASSESMAYBEUSEDISINCLUDEDELSEWHEREINTHISCHAPTERJSP1211JSPPAGESYNTAXPUBLICINTERFACEJSPPAGEEXTENDSJAVAXSERVLETSERVLETALLKNOWNSUBINTERFACESHTTPJSPPAGEALLSUPERINTERFACESJAVAXSERVLETSERVLETDESCRIPTIONTHEJSPPAGEINTERFACEDESCRIBESTHEGENERICINTERACTIONTHATAJSPPAGEIMPLEMENTATIONCLASSMUSTSATISFYPAGESTHATUSETHEHTTPPROTOCOLAREDESCRIBEDBYTHEHTTPJSPPAGEINTERFACETWOPLUSONEMETHODSTHEINTERFACEDEFINESAPROTOCOLWITH3METHODSONLYTWOOFTHEMJSPINITANDJSPDESTROYAREPARTOFTHISINTERFACEASTHESIGNATUREOFTHETHIRDMETHOD_JSPSERVICEDEPENDSONTHESPECIFICPROTOCOLUSEDANDCANNOTBEEXPRESSEDINAGENERICWAYINJAVAACLASSIMPLEMENTINGTHISINTERFACEISRESPONSIBLEFORINVOKINGTHEABOVEMETHODSATTHEAPPROPRIATETIMEBASEDONTHECORRESPONDINGSERVLETBASEDMETHODINVOCATIONSTHEJSPINITANDJSPDESTROYMETHODSCANBEDEFINEDBYAJSPAUTHOR,BUTTHE_JSPSERVICEMETHODISDEFINEDAUTOMATICALLYBYTHEJSPPROCESSORBASEDONTHECONTENTSOFTHEJSPPAGE_JSPSERVICETHE_JSPSERVICEMETHODCORRESPONDSTOTHEBODYOFTHEJSPPAGETHISMETHODISDEFINEDAUTOMATICALLYBYTHEJSPCONTAINERANDSHOULDNEVERBEDEFINEDBYTHEJSPPAGEAUTHORIFASUPERCLASSISSPECIFIEDUSINGTHEEXTENDSATTRIBUTE,THATSUPERCLASSMAYCHOOSETOPERFORMSOMEACTIONSINITSSERVICEMETHODBEFOREORAFTERCALLINGTHE_JSPSERVICEMETHODSEEUSINGTHEEXTENDSATTRIBUTEINTHEJSP_ENGINECHAPTEROFTHEJSPSPECIFICATIONTHESPECIFICSIGNATUREDEPENDSONTHEPROTOCOLSUPPORTEDBYTHEJSPPAGEPUBLICVOID_JSPSERVICESERVLETREQUESTSUBTYPEREQUEST,SERVLETRESPONSESUBTYPERESPONSETHROWSSERVLETEXCEPTION,IOEXCEPTIONJSP12111METHODSPUBLICVOIDJSPDESTROYTHEJSPDESTROYMETHODISINVOKEDWHENTHEJSPPAGEISABOUTTOBEDESTROYEDAJSPPAGECANOVERRIDETHISMETHODBYINCLUDINGADEFINITIONFORITINADECLARATIONELEMENTAJSPPAGESHOULDREDEFINETHEDESTROYMETHODFROMSERVLETJSPPAGEIMPLEMENTATIONOBJECTCONTRACTPUBLICVOIDJSPINITTHEJSPINITMETHODISINVOKEDWHENTHEJSPPAGEISINITIALIZEDITISTHERESPONSIBILITYOFTHEJSPIMPLEMENTATIONANDOFTHECLASSMENTIONEDBYTHEEXTENDSATTRIBUTE,IFPRESENTTHATATTHISPOINTINVOCATIONSTOTHEGETSERVLETCONFIGMETHODWILLRETURNTHEDESIREDVALUEAJSPPAGECANOVERRIDETHISMETHODBYINCLUDINGADEFINITIONFORITINADECLARATIONELEMENTAJSPPAGESHOULDREDEFINETHEINITMETHODFROMSERVLETJSP1212HTTPJSPPAGESYNTAXPUBLICINTERFACEHTTPJSPPAGEEXTENDSJSPPAGEALLSUPERINTERFACESJSPPAGE,JAVAXSERVLETSERVLETDESCRIPTIONTHEHTTPJSPPAGEINTERFACEDESCRIBESTHEINTERACTIONTHATAJSPPAGEIMPLEMENTATIONCLASSMUSTSATISFYWHENUSINGTHEHTTPPROTOCOLTHEBEHAVIOURISIDENTICALTOTHATOFTHEJSPPAGE,EXCEPTFORTHESIGNATUREOFTHE_JSPSERVICEMETHOD,WHICHISNOWEXPRESSIBLEINTHEJAVATYPESYSTEMANDINCLUDEDEXPLICITLYINTHEINTERFACESEEALSOJSPPAGEJSP12121METHODSPUBLICVOID_JSPSERVICEJAVAXSERVLETHTTPHTTPSERVLETREQUESTREQUEST,JAVAXSERVLETHTTPHTTPSERVLETRESPONSERESPONSETHE_JSPSERVICEMETHODCORRESPONDSTOTHEBODYOFTHEJSPPAGETHISMETHODISDEFINEDAUTOMATICALLYBYTHEJSPCONTAINERANDSHOULDNEVERBEDEFINEDBYTHEJSPPAGEAUTHORIFASUPERCLASSISSPECIFIEDUSINGTHEEXTENDSATTRIBUTE,THATSUPERCLASSMAYCHOOSETOPERFORMSOMEACTIONSINITSSERVICEMETHODBEFOREORAFTERCALLINGTHE_JSPSERVICEMETHODSEEUSINGTHEEXTENDSATTRIBUTEINTHEJSP_ENGINECHAPTEROFTHEJSPSPECIFICATIONPARAMETERSREQUESTPROVIDESCLIENTREQUESTINFORMATIONTOTHEJSPRESPONSEASSISTSTHEJSPINSENDINGARESPONSETOTHECLIENTTHROWSSERVLETEXCEPTIONTHROWNIFANERROROCCURREDDURINGTHEPROCESSINGOFTHEJSPANDTHATTHECONTAINERSHOULDTAKEAPPROPRIATEACTIONTOCLEANUPTHEREQUESTIOEXCEPTIONTHROWNIFANERROROCCURREDWHILEWRITINGTHERESPONSEFORTHISPAGEJSP1213JSPFACTORYSYNTAXPUBLICABSTRACTCLASSJSPFACTORYDESCRIPTIONTHEJSPFACTORYISANABSTRACTCLASSTHATDEFINESANUMBEROFFACTORYMETHODSAVAILABLETOAJSPPAGEATRUNTIMEFORTHEPURPOSESOFCREATINGINSTANCESOFVARIOUSINTERFACESANDCLASSESUSEDTOSUPPORTTHEJSPIMPLEMENTATIONACONFORMANTJSPENGINEIMPLEMENTATIONWILL,DURINGITSINITIALIZATIONINSTANTIATEANIMPLEMENTATIONDEPENDENTSUBCLASSOFTHISCLASS,ANDMAKEITGLOBALLYAVAILABLEFORUSEBYJSPIMPLEMENTATIONCLASSESBYREGISTERINGTHEINSTANCECREATEDWITHTHISCLASSVIATHESTATICSETDEFAULTFACTORYMETHODTHEPAGECONTEXTANDTHEJSPENGINEINFOCLASSESARETHEONLYIMPLEMENTATIONDEPENDENTCLASSESTHATCANBECREATEDFROMTHEFACTORYJSPFACTORYOBJECTSSHOULDNOTBEUSEDBYJSPPAGEAUTHORSJSP12131CONSTRUCTORSPUBLICJSPFACTORYSOLECONSTRUCTORFORINVOCATIONBYSUBCLASSCONSTRUCTORS,TYPICALLYIMPLICITJSP12132METHODSPUBLICSTATICSYNCHRONIZEDJSPFACTORYGETDEFAULTFACTORYRETURNSTHEDEFAULTFACTORYFORTHISIMPLEMENTATIONRETURNSTHEDEFAULTFACTORYFORTHISIMPLEMENTATIONPUBLICABSTRACTJSPENGINEINFOGETENGINEINFOCALLEDTOGETIMPLEMENTATIONSPECIFICINFORMATIONONTHECURRENTJSPENGINERETURNSAJSPENGINEINFOOBJECTDESCRIBINGTHECURRENTJSPENGINEPUBLICABSTRACTPAGECONTEXTGETPAGECONTEXTJAVAXSERVLETSERVLETSERVLET,JAVAXSERVLETSERVLETREQUESTREQUEST,JAVAXSERVLETSERVLETRESPONSERESPONSE,JAVALANGSTRINGERRORPAGEURL,BOOLEANNEEDSSESSION,INTBUFFER,BOOLEANAUTOFLUSHOBTAINSANINSTANCEOFANIMPLEMENTATIONDEPENDENTJAVAXSERVLETJSPPAGECONTEXTABSTRACTCLASSFORTHECALLINGSERVLETANDCURRENTLYPENDINGREQUESTANDRESPONSETHISMETHODISTYPICALLYCALLEDEARLYINTHEPROCESSINGOFTHE_JSPSERVICEMETHODOFAJSPIMPLEMENTATIONCLASSINORDERTOOBTAINAPAGECONTEXTOBJECTFORTHEREQUESTBEINGPROCESSEDINVOKINGTHISMETHODSHALLRESULTINTHEPAGECONTEXTINITIALIZEMETHODBEINGINVOKEDTHEPAGECONTEXTRETURNEDISPROPERLYINITIALIZEDALLPAGECONTEXTOBJECTSOBTAINEDVIATHISMETHODSHALLBERELEASEDBYINVOKINGRELEASEPAGECONTEXTPARAMETERSSERVLETTHEREQUESTINGSERVLETREQUESTTHECURRENTREQUESTPENDINGONTHESERVLETRESPONSETHECURRENTRESPONSEPENDINGONTHESERVLETERRORPAGEURLTHEURLOFTHEERRORPAGEFORTHEREQUESTINGJSP,ORNULLNEEDSSESSIONTRUEIFTHEJSPPARTICIPATESINASESSIONBUFFERSIZEOFBUFFERINBYTES,PAGECONTEXTNO_BUFFERIFNOBUFFER,PAGECONTEXTDEFAULT_BUFFERIFIMPLEMENTATIONDEFAULTAUTOFLUSHSHOULDTHEBUFFERAUTOFLUSHTOTHEOUTPUTSTREAMONBUFFEROVERFLOW,ORTHROWANIOEXCEPTIONRETURNSTHEPAGECONTEXTSEEALSOPAGECONTEXTPUBLICABSTRACTVOIDRELEASEPAGECONTEXTPAGECONTEXTPCCALLEDTORELEASEAPREVIOUSLYALLOCATEDPAGECONTEXTOBJECTRESULTSINPAGECONTEXTRELEASEBEINGINVOKEDTHISMETHODSHOULDBEINVOKEDPRIORTORETURNINGFROMTHE_JSPSERVICEMETHODOFAJSPIMPLEMENTATIONCLASSPARAMETERSPCAPAGECONTEXTPREVIOUSLYOBTAINEDBYGETPAGECONTEXTPUBLICSTATICSYNCHRONIZEDVOIDSETDEFAULTFACTORYJSPFACTORYDEFLTSETTHEDEFAULTFACTORYFORTHISIMPLEMENTATIONITISILLEGALFORANYPRINCIPALOTHERTHANTHEJSPENGINERUNTIMETOCALLTHISMETHODPARAMETERSDEFLTTHEDEFAULTFACTORYIMPLEMENTATIONJSP1214JSPENGINEINFOSYNTAXPUBLICABSTRACTCLASSJSPENGINEINFODESCRIPTIONTHEJSPENGINEINFOISANABSTRACTCLASSTHATPROVIDESINFORMATIONONTHECURRENTJSPENGINEJSP12141CONSTRUCTORSPUBLICJSPENGINEINFOSOLECONSTRUCTORFORINVOCATIONBYSUBCLASSCONSTRUCTORS,TYPICALLYIMPLICITJSP12142METHODSPUBLICABSTRACTJAVALANGSTRINGGETSPECIFICATIONVERSIONRETURNTHEVERSIONNUMBEROFTHEJSPSPECIFICATIONTHATISSUPPORTEDBYTHISJSPENGINESPECIFICATIONVERSIONNUMBERSTHATCONSISTSOFPOSITIVEDECIMALINTEGERSSEPARATEDBYPERIODS“”,FOREXAMPLE,“20”OR“1234567”THISALLOWSANEXTENSIBLENUMBERTOBEUSEDTOREPRESENTMAJOR,MINOR,MICRO,ETCVERSIONSTHEVERSIONNUMBERMUSTBEGINWITHANUMBERRETURNSTHESPECIFICATIONVERSION,NULLISRETURNEDIFITISNOTKNOWNJSP122IMPLICITOBJECTSTHEPAGECONTEXTOBJECTANDTHEJSPWRITERAREAVAILABLEBYDEFAULTASIMPLICITOBJECTSJSP1221JSPCONTEXTSYNTAXPUBLICABSTRACTCLASSJSPCONTEXTDIRECTKNOWNSUBCLASSESPAGECONTEXTDESCRIPTIONJSPCONTEXTSERVESASTHEBASECLASSFORTHEPAGECONTEXTCLASSANDABSTRACTSALLINFORMATIONTHATISNOTSPECIFICTOSERVLETSTHISALLOWSFORSIMPLETAGEXTENSIONSTOBEUSEDOUTSIDEOFTHECONTEXTOFAREQUEST/RESPONSESERVLETTHEJSPCONTEXTPROVIDESANUMBEROFFACILITIESTOTHEPAGE/COMPONENTAUTHORANDPAGEIMPLEMENTOR,INCLUDINGASINGLEAPITOMANAGETHEVARIOUSSCOPEDNAMESPACESAMECHANISMTOOBTAINTHEJSPWRITERFOROUTPUTAMECHANISMTOEXPOSEPAGEDIRECTIVEATTRIBUTESTOTHESCRIPTINGENVIRONMENTMETHODSINTENDEDFORCONTAINERGENERATEDCODETHEFOLLOWINGMETHODSENABLETHEMANAGEMENTOFNESTEDJSPWRITERSTREAMSTOIMPLEMENTTAGEXTENSIONSPUSHBODYANDPOPBODYMETHODSINTENDEDFORJSPAUTHORSSOMEMETHODSPROVIDEUNIFORMACCESSTOTHEDIVERSEOBJECTSREPRESENTINGSCOPESTHEIMPLEMENTATIONMUSTUSETHEUNDERLYINGMACHINERYCORRESPONDINGTOTHATSCOPE,SOINFORMATIONCANBEPASSEDBACKANDFORTHBETWEENTHEUNDERLYINGENVIRONMENTEGSERVLETSANDJSPPAGESTHEMETHODSARESETATTRIBUTE,GETATTRIBUTE,FINDATTRIBUTE,REMOVEATTRIBUTE,GETATTRIBUTESSCOPEANDGETATTRIBUTENAMESINSCOPETHEFOLLOWINGMETHODSPROVIDECONVENIENTACCESSTOIMPLICITOBJECTSGETOUTTHEFOLLOWINGMETHODSPROVIDEPROGRAMMATICACCESSTOTHEEXPRESSIONLANGUAGEEVALUATORGETEXPRESSIONEVALUATOR,GETVARIABLERESOLVERSINCE20JSP12211CONSTRUCTORSPUBLICJSPCONTEXTSOLECONSTRUCTORFORINVOCATIONBYSUBCLASSCONSTRUCTORS,TYPICALLYIMPLICITJSP12212METHODSPUBLICABSTRACTJAVALANGOBJECTFINDATTRIBUTEJAVALANGSTRINGNAMESEARCHESFORTHENAMEDATTRIBUTEINPAGE,REQUEST,SESSIONIFVALID,ANDAPPLICATIONSCOPESINORDERANDRETURNSTHEVALUEASSOCIATEDORNULLPARAMETERSNAMETHENAMEOFTHEATTRIBUTETOSEARCHFORRETURNSTHEVALUEASSOCIATEDORNULLTHROWSNULLPOINTEREXCEPTIONIFTHENAMEISNULLPUBLICABSTRACTJAVALANGOBJECTGETATTRIBUTEJAVALANGSTRINGNAMERETURNSTHEOBJECTASSOCIATEDWITHTHENAMEINTHEPAGESCOPEORNULLIFNOTFOUNDPARAMETERSNAMETHENAMEOFTHEATTRIBUTETOGETRETURNSTHEOBJECTASSOCIATEDWITHTHENAMEINTHEPAGESCOPEORNULLIFNOTFOUNDTHROWSNULLPOINTEREXCEPTIONIFTHENAMEISNULLPUBLICABSTRACTJAVALANGOBJECTGETATTRIBUTEJAVALANGSTRINGNAME,INTSCOPERETURNTHEOBJECTASSOCIATEDWITHTHENAMEINTHESPECIFIEDSCOPEORNULLIFNOTFOUNDPARAMETERSNAMETHENAMEOFTHEATTRIBUTETOSETSCOPETHESCOPEWITHWHICHTOASSOCIATETHENAME/OBJECTRETURNSTHEOBJECTASSOCIATEDWITHTHENAMEINTHESPECIFIEDSCOPEORNULLIFNOTFOUNDTHROWSNULLPOINTEREXCEPTIONIFTHENAMEISNULLILLEGALARGUMENTEXCEPTIONIFTHESCOPEISINVALIDILLEGALSTATEEXCEPTIONIFTHESCOPEISPAGECONTEXTSESSION_SCOPEBUTTHEPAGETHATWASREQUESTEDDOESNOTPARTICIPATEINASESSIONORTHESESSIONHASBEENINVALIDATEDPUBLICABSTRACTJAVAUTILENUMERATIONGETATTRIBUTENAMESINSCOPEINTSCOPEENUMERATEALLTHEATTRIBUTESINAGIVENSCOPEPARAMETERSSCOPETHESCOPETOENUMERATEALLTHEATTRIBUTESFORRETURNSANENUMERATIONOFNAMESJAVALANGSTRINGOFALLTHEATTRIBUTESTHESPECIFIEDSCOPETHROWSILLEGALARGUMENTEXCEPTIONIFTHESCOPEISINVALIDILLEGALSTATEEXCEPTIONIFTHESCOPEISPAGECONTEXTSESSION_SCOPEBUTTHEPAGETHATWASREQUESTEDDOESNOTPARTICIPATEINASESSIONORTHESESSIONHASBEENINVALIDATEDPUBLICABSTRACTINTGETATTRIBUTESSCOPEJAVALANGSTRINGNAMEGETTHESCOPEWHEREAGIVENATTRIBUTEISDEFINEDPARAMETERSNAMETHENAMEOFTHEATTRIBUTETORETURNTHESCOPEFORRETURNSTHESCOPEOFTHEOBJECTASSOCIATEDWITHTHENAMESPECIFIEDOR0THROWSNULLPOINTEREXCEPTIONIFTHENAMEISNULLPUBLICABSTRACTEXPRESSIONEVALUATORGETEXPRESSIONEVALUATORPROVIDESPROGRAMMATICACCESSTOTHEEXPRESSIONEVALUATORTHEJSPCONTAINERMUSTRETURNAVALIDINSTANCEOFANEXPRESSIONEVALUATORTHATCANPARSEELEXPRESSIONSRETURNSAVALIDINSTANCEOFANEXPRESSIONEVALUATORSINCE20PUBLICABSTRACTJSPWRITERGETOUTTHECURRENTVALUEOFTHEOUTOBJECTAJSPWRITERRETURNSTHECURRENTJSPWRITERSTREAMBEINGUSEDFORCLIENTRESPONSEPUBLICABSTRACTVARIABLERESOLVERGETVARIABLERESOLVERRETURNSANINSTANCEOFAVARIABLERESOLVERTHATPROVIDESACCESSTOTHEIMPLICITOBJECTSSPECIFIEDINTHEJSPSPECIFICATIONUSINGTHISJSPCONTEXTASTHECONTEXTOBJECTRETURNSAVALIDINSTANCEOFAVARIABLERESOLVERSINCE20PUBLICJSPWRITERPOPBODYRETURNTHEPREVIOUSJSPWRITER“OUT”SAVEDBYTHEMATCHINGPUSHBODY,ANDUPDATETHEVALUEOFTHE“OUT”ATTRIBUTEINTHEPAGESCOPEATTRIBUTENAMESPACEOFTHEJSPCONTEXTRETURNSTHESAVEDJSPWRITERPUBLICJSPWRITERPUSHBODYJAVAIOWRITERWRITERRETURNANEWJSPWRITEROBJECTTHATSENDSOUTPUTTOTHEPROVIDEDWRITERSAVESTHECURRENT“OUT”JSPWRITER,ANDUPDATESTHEVALUEOFTHE“OUT”ATTRIBUTEINTHEPAGESCOPEATTRIBUTENAMESPACEOFTHEJSPCONTEXTTHERETURNEDJSPWRITERMUSTIMPLEMENTALLMETHODSANDBEHAVEASTHOUGHITWEREUNBUFFEREDMORESPECIFICALLYCLEARMUSTTHROWANIOEXCEPTIONCLEARBUFFERDOESNOTHINGGETBUFFERSIZEALWAYSRETURNS0GETREMAININGALWAYSRETURNS0PARAMETERSWRITERTHEWRITERFORTHERETURNEDJSPWRITERTOSENDOUTPUTTORETURNSANEWJSPWRITERTHATWRITESTOTHEGIVENWRITERSINCE20PUBLICABSTRACTVOIDREMOVEATTRIBUTEJAVALANGSTRINGNAMEREMOVETHEOBJECTREFERENCEASSOCIATEDWITHTHEGIVENNAMEFROMALLSCOPESDOESNOTHINGIFTHEREISNOSUCHOBJECTPARAMETERSNAMETHENAMEOFTHEOBJECTTOREMOVETHROWSNULLPOINTEREXCEPTIONIFTHENAMEISNULLPUBLICABSTRACTVOIDREMOVEATTRIBUTEJAVALANGSTRINGNAME,INTSCOPEREMOVETHEOBJECTREFERENCEASSOCIATEDWITHTHESPECIFIEDNAMEINTHEGIVENSCOPEDOESNOTHINGIFTHEREISNOSUCHOBJECTPARAMETERSNAMETHENAMEOFTHEOBJECTTOREMOVESCOPETHESCOPEWHERETOLOOKTHROWSILLEGALARGUMENTEXCEPTIONIFTHESCOPEISINVALIDILLEGALSTATEEXCEPTIONIFTHESCOPEISPAGECONTEXTSESSION_SCOPEBUTTHEPAGETHATWASREQUESTEDDOESNOTPARTICIPATEINASESSIONORTHESESSIONHASBEENINVALIDATEDNULLPOINTEREXCEPTIONIFTHENAMEISNULLPUBLICABSTRACTVOIDSETATTRIBUTEJAVALANGSTRINGNAME,JAVALANGOBJECTVALUEREGISTERTHENAMEANDVALUESPECIFIEDWITHPAGESCOPESEMANTICSIFTHEVALUEPASSEDINISNULL,THISHASTHESAMEEFFECTASCALLINGREMOVEATTRIBUTENAME,PAGECONTEXTPAGE_SCOPEPARAMETERSNAMETHENAMEOFTHEATTRIBUTETOSETVALUETHEVALUETOASSOCIATEWITHTHENAME,ORNULLIFTHEATTRIBUTEISTOBEREMOVEDFROMTHEPAGESCOPETHROWSNULLPOINTEREXCEPTIONIFTHENAMEISNULLPUBLICABSTRACTVOIDSETATTRIBUTEJAVALANGSTRINGNAME,JAVALANGOBJECTVALUE,INTSCOPEREGISTERTHENAMEANDVALUESPECIFIEDWITHAPPROPRIATESCOPESEMANTICSIFTHEVALUEPASSEDINISNULL,THISHASTHESAMEEFFECTASCALLINGREMOVEATTRIBUTENAME,SCOPEPARAMETERSNAMETHENAMEOFTHEATTRIBUTETOSETVALUETHEOBJECTTOASSOCIATEWITHTHENAME,ORNULLIFTHEATTRIBUTEISTOBEREMOVEDFROMTHESPECIFIEDSCOPESCOPETHESCOPEWITHWHICHTOASSOCIATETHENAME/OBJECTTHROWSNULLPOINTEREXCEPTIONIFTHENAMEISNULLILLEGALARGUMENTEXCEPTIONIFTHESCOPEISINVALIDILLEGALSTATEEXCEPTIONIFTHESCOPEISPAGECONTEXTSESSION_SCOPEBUTTHEPAGETHATWASREQUESTEDDOESNOTPARTICIPATEINASESSIONORTHESESSIONHASBEENINVALIDATEDJSP1222PAGECONTEXTSYNTAXPUBLICABSTRACTCLASSPAGECONTEXTEXTENDSJSPCONTEXTDESCRIPTIONPAGECONTEXTEXTENDSJSPCONTEXTTOPROVIDEUSEFULCONTEXTINFORMATIONFORWHENJSPTECHNOLOGYISUSEDINASERVLETENVIRONMENTAPAGECONTEXTINSTANCEPROVIDESACCESSTOALLTHENAMESPACESASSOCIATEDWITHAJSPPAGE,PROVIDESACCESSTOSEVERALPAGEATTRIBUTES,ASWELLASALAYERABOVETHEIMPLEMENTATIONDETAILSIMPLICITOBJECTSAREADDEDTOTHEPAGECONTEXTAUTOMATICALLYTHEPAGECONTEXTCLASSISANABSTRACTCLASS,DESIGNEDTOBEEXTENDEDTOPROVIDEIMPLEMENTATIONDEPENDENTIMPLEMENTATIONSTHEREOF,BYCONFORMANTJSPENGINERUNTIMEENVIRONMENTSAPAGECONTEXTINSTANCEISOBTAINEDBYAJSPIMPLEMENTATIONCLASSBYCALLINGTHEJSPFACTORYGETPAGECONTEXTMETHOD,ANDISRELEASEDBYCALLINGJSPFACTORYRELEASEPAGECONTEXTANEXAMPLEOFHOWPAGECONTEXT,JSPFACTORY,ANDOTHERCLASSESCANBEUSEDWITHINAJSPPAGEIMPLEMENTATIONOBJECTISGIVENELSEWHERETHEPAGECONTEXTPROVIDESANUMBEROFFACILITIESTOTHEPAGE/COMPONENTAUTHORANDPAGEIMPLEMENTOR,INCLUDINGASINGLEAPITOMANAGETHEVARIOUSSCOPEDNAMESPACESANUMBEROFCONVENIENCEAPISTOACCESSVARIOUSPUBLICOBJECTSAMECHANISMTOOBTAINTHEJSPWRITERFOROUTPUTAMECHANISMTOMANAGESESSIONUSAGEBYTHEPAGEAMECHANISMTOEXPOSEPAGEDIRECTIVEATTRIBUTESTOTHESCRIPTINGENVIRONMENTMECHANISMSTOFORWARDORINCLUDETHECURRENTREQUESTTOOTHERACTIVECOMPONENTSINTHEAPPLICATIONAMECHANISMTOHANDLEERROR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